In general, the present invention relates to an information processing technology which is capable of recording and reproducing information with a high degree of reliability. More particularly, the present invention relates to a wobble signal detecting circuit for detecting a wobble signal obtained from a recording medium such as a disk, a wobble abnormality detecting circuit for detecting an abnormality of the wobble signal, an information processing apparatus or method using these wobble signal and wobble abnormality detecting circuits and a recording medium used in the apparatus or method.
As a recording medium used in recording and playback operations, there has been developed a recording medium that is provided with groove tracks as well as land tracks created on a board thereof and infinitesimally wobbling in the radial direction and provided with information recording areas on both the groove and land (inter-groove) tracks. The recording medium has a predetermined wobble pattern. In a recording or playback operation, by using a wobble signal based on this wobble pattern, position information or a position signal is obtained. An operation to record or play back information is based on the position signal.
In the conventional technology, a wobble signal based on a wobble pattern originated from such a recording medium may not be generated normally due to a defect on the recording medium or a control deviation occurring in a playback operation, resulting in a miss which gives rise to a problem that position information or a position signal can not be obtained in a recording or playback operation.